Rotor construction



y 1962 R. L. ROWLEY 3,034,763

ROTOR CONSTRUCTION Filed Aug. 20, 1959 lNVENTOR ROBERT L. POM LEV y C404 ATTORNEY United States Patent 3,034,763 ROTOR CONSTRUCTION Robert L. Rowley, South Glastonbury, Conn., assignor to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Filed Aug. 20, 1959, Ser. No. 835,132 2 Claims. (11. 253-47 This invention relates to a rotor construction for an axial flow compressor or turbine.

One feature of the invention is a mounting for a blade on a supporting disc by which to minimize any circulation flow below the blade platform. Another feature is a blade mounting in which the disc construction serves as a retainer for axial blade movement in one direction. Another feature is a Ininimum weight, maximum load disc and blade assembly where the blade platform makes an acute angle with the disc axis.

One particular feature is an arrangement by which to minimize the rigidity difference of the disc at the dovetail and between the dovetail slots that support the blades.

Other features and advantages will be apparent from the following description taken in conjunction with the accompanying drawing in which:

FIG. 1 is a longitudinal sectional view through a compressor disc.

FIG. 2 is a perspective view of a portion of the periphery of the disc with the blade attached thereto.

FIG. 3 is a sectional view substantially along the line of 3-3 of FIG. 1.

FIG. 4 is a sectional view substantially along the line of 44 of FIG. 3.

The drawing shows in FIG. 1 only a sectional view of the disc from the axis of the disc to the periphery. The disc 2 is generally flat being thickened as to 4 adjacent to the center for stress purposes. The disc may also carry projecting ribs 6 on opposite sides for positioning the disc in a complete rotor assembly. A rotor assembly to which this disc is applicable is described in the Ledwith Patent 2,639,885.

The periphery 8 of the disc is thickened in an axial direction and has a plurality of peripheral axially extending slots 10 to receive the blade roots 12 on the blades 14. These slots and blade roots may be of any conventional arrangement; the particular shape is the usual dovetail root. The root 12 may have at one end a projecting flange 16 to overlie the end surface 18 of the disc thereby to prevent axial movement of the blade in one direction (to the right in FIG. 1). A blade locking strip 28 overlies the opposite end surface 22 of the disc and has its opposite end received in a radially extending opening 24 in the blade root to limit axial movement in the other direction (to the left, FIG. 1).

Between the operative air-foil portion of the blade and the blade root 12 is the blade platform 26 which defines the interior wall of the gas path past the blade. This platform in the arrangement shown extends at an acute angle to the axis of the disc as viewed in a longitudinal axial plane as in FIG. '1. The several platforms 26 for the row of blades 14 on the disc 2 thus define substantially a cone concentric to the rotor axis. Thus the spacing of each platform 26 from the axis in a radial direction increases from one end of the platform to the other. To prevent the leakage of air past the disc between the periphery of the latter and the platform 26 the disc has axially spaced flanges 28 and 30 projecting radially from the disc and in engagement with the underside of the platform as best shown in FIG. 1.

3,034,763 Patented May 15, 1962 ice The rib or flange 30 is higher than the flange 28 because of the greater spacing of the platform 26 from the disc axis at the flange 30. The flanges 28 and 30 are preferably located in alignment with the opposite end surfaces 18 and 22 of the disc. Between the flanges 28 and 30 the peripheral surface 32 of the disc is preferably parallel to the axis of the disc. This peripheral surface 32 is located as close to the axis as possible and still provide adequate strength to the disc to support the blade dovetails. By minimizing the distance from the bottom surface 34 of each slot 10 to the peripheral surface 32 the rigidity ditferences between the disc section at each dovetail slot and the disc section between the dovetail slots are minimized thereby minimizing the stress concentration factor at dovetails during disc vibration. The periphery of the flanges 28 and 30 are arcuate about the axis of the disc and each flange defines a circle concentric to the axis of the disc.

As will be apparent from FIGS. 3 and 4 the slots 10 and blade roots 12 may not be exactly at right angles to the plane of the disc but may be positioned at a slight angle thereto. Similarly the opposite side edges 36 of the blade platform 26 may extend parallel to the root. It will be understood that the contiguous edges of adjacent platforms are substantially in contact with one another.

It is to be understood that the invention is not limited to the specific embodiment herein illustrated and described, but may be used in other ways without departure from its spirit as defined by the following claims.

I claim:

1. An axial flow turbine or compressor rotor including a disc having a row of blades projecting outward from its periphery, each blade having an operative blade portion, a root portion, and a platform integral therewith located between the blade portion and the root portion, the underside of the platform extending at an acute angle to the axis of the disc in an axial direction such that one end of the platform is located at a greater radial distance from the axis than the other end of the platform, the disc having a series of axially extending peripheral slots substantially the same shape as the root portions to receive said root portions therein, and axially spaced peripheral flanges on the disc between adjacent slots for engagement with the underside of the platforms, the periphery of said flanges being substantially arcuate about the axis of the disc, one of the peripheral flanges having a greater radial dimension than the other thereby to limit the axial movement of the blade root in one direction with respect to the disc.

2. An axial flow turbine or compressor rotor including a disc having a row of blades projecting outward from its periphery, each blade having an operative blade portion, a root portion, and a platform integral therewith located between the blade portion and the root portion, the underside of the platform extending at an acute angle to the axis of the disc in an axial direction such that one end of the platform is located at a greater radial distance from the axis than the other end of the platform, the disc having a series of axially extending peripheral slots substantially the same shape as the root portions to receive said root portions therein, and axially spaced peripheral flanges on the disc between adjacent slots for engagement with the underside of the platforms, the periphery of said flanges being substantially arcuate about the axis of the disc, one of the peripheral flanges having a greater radial dimension than the other thereby to limit the axial movement of the blade root in one direction with respect to the disc, the periphery of the disc between the flanges being cylindrical.

References Cited in the file of this patent UNITED STATES PATENTS 4 Ledwith June 19, 1956 Zimmerman Sept. 24, 1957 Davies et a1. Oct. 27, 1959 FOREIGN PATENTS Great Britain Mar. 12, 1952 France Nov. 18, 1953 

